I have been preaching a version of that gospel for some time. The basic problem comes not from the proposed regulations but from 403(b)(5), which says that two or more contracts are treated as one contract under 403(b) and which has been ignored in the past. In a multi-vendor environment, the contracts may individually meet the requirements of 403(b), but in the aggregate they are going to have limitations that exceed 403(b). Also, on the distribution side, they are going to permit excessive loans, etc.
One vendor is one solution, but not the only one, and not one that is available at all if the employer (e.g., a school district) has to allow multiple vendors. Another, which we do here, is to create a wraparound plan (or non-plan) document, under which the various vendors have something like the status of a trustee under a qualified plan, and to route loans and distributions through an administrator that ensures compliance with dollar limits and prevents multiple hardship distributions.
Tom Geer